HashTable に関する質問です

前提・実現したいこと

HashTable の #keys(key を全て取り出したい) と #loadFactor(bucket のサイズの平均値を求めたい)を実装したいのですが、どうすればよいのかさっぱり分かりません。アイデアを頂けないでしょうか？

HashTableEntry

Java
public class HashTableEntry<K, V> {

    private K key;
    private V value;
    private int hash;

    public HashTableEntry(K key, V value) {
        if (key == null)
            throw new IllegalArgumentException("key cannot be null");

        this.key = key;
        this.value = value;
        this.hash = key.hashCode();
    }

    public K getKey() {
        return this.key;
    }

    public V getValue() {
        return this.value;
    }

    public int getHashCode() {
        return this.hash;
    }

    public String toString() {
        return "{" + key + ": " + value + " (" + hash + ")}";
    }

}

HashTable

Java
import java.util.List;
import java.util.LinkedList;
import java.util.Arrays;


public class HashTable<K, V> {

    private Object[] entries;

    private List<HashTableEntry<K, V>> bucket(int i) {
        return (List<HashTableEntry<K, V>>)entries[i];
    }

    public HashTable(int numBuckets) {
        if (numBuckets < 1)
            throw new IllegalArgumentException("hash table must have at least one bucket");
        this.entries = new Object[numBuckets];
        for (int i = 0; i < numBuckets; i++)
            this.entries[i] = new LinkedList<HashTableEntry<K, V>>();
    }

    public void put(K key, V value) {
        HashTableEntry<K, V> e = new HashTableEntry<K, V>(key, value);
        int h = e.getHashCode();
        int b = Math.abs(h % this.entries.length);
        bucket(b).add(e);
    }

    public V get(K key) {
        int h = key.hashCode();
        int b = Math.abs(h % this.entries.length);
        for (HashTableEntry<K, V> e : bucket(b))
            if (key.equals(e.getKey()))
                return e.getValue();
        return null;
    }

    public List<K> keys() {
        List<K> klist = new LinkedList<K>();
    }

    public double loadFactor() {
        double sum = 0;
    }